#!/bin/bash
#for 
for loop in 1 2 3 4
do
	echo "$loop"
done
#======================
#while
a=1
while (( $a<=5 )) 
do
	echo $a
done
while true
do
    command
done

#=====================
until (( condition )) 
do
	#statements
done
#======================
#case
echo '输入1到4之间的数字：'
echo '你输入的数字为：'
read aNum
case $anum in
	1 ) echo '数字1'
		;;
	2 ) echo '数字2'
		;;
	3 ) echo '数字3'
		;;
	4 ) echo '数字4'
		;;
	* ) echo '不是1到4之间的数字'
		;;
esac